Water-soluble or water-dispersible polyurethanes with terminal acid groups, the production and the use thereof

ABSTRACT

The present invention relates to water-soluble or water-dispersible polyurethanes of a water-dispersible polyurethane prepolymer having terminal isocyanate groups and a primary or secondary amine having at least one ionogenic or ionic group, and to the salts thereof. The novel polyurethanes can be used as auxiliaries in cosmetology and pharmacy and, in particular, as hair lacquers having enhanced ease of washoff.

The present present invention relates to water-soluble orwater-dispersible polyurethanes with terminal acid groups, to theirpreparation and to their use in cosmetology.

Water-soluble or water-dispersible polymers, for example polyesters,polyamides or polyurethanes, are becoming increasingly important on thebasis of their particularly low viscosity in water/ethanol. Forinstance, water-soluble polyurethanes comprising carboxyl-containingdiols in copolymerized form are disclosed in U.S. Pat. Nos. 3,412,054and 3,658,939. They are used as adhesives, as coating compositions andin printing inks. Water-dispersible polyurethanes containing sulfonategroups and/or carboxylate groups are disclosed in DE-A-15 70 615. Theyare used, for example, for coating and for the impregnation of textiles,leather, paper, wood and metals. Patent documents U.S. Pat. No.4,300,580, U.S. Pat. No. 3,734,874, DE-A-26 33 418 and WO-A-89/07118disclose polyesters which contain NaSO₃ groups and whose main chain issynthesized by condensation reaction and can be broken into shortersegments by hydrolyzing the ester groups.

It is also known that maleic anhydride and trimellitic anhydride can beused to prepare water-soluble esters. The anhydride group providescarboxyl groups which, by neutralization with amines, metal hydroxidesand metal carbonates, are converted to water-solubilizing carboxylategroups. DE-A-26 37 167 and U.S. Pat. No. 3,523,998 disclose thatpolycarboxylic acids and their anhydrides can, as polymer components,also contribute to rendering polyesters soluble in water. DE-A-21 44 878describes polyurethanes which are reaction products of digested casein,water-dispersible polyurethanes and formaldehyde. The polyurethanecomponent employed is, inter alia, a latex obtainable by reacting apolyurethane prepolymer with a sodium taurine solution. The latex has arelatively low molecular weight and a low content of ionogenic or ionicgroups, since other than the sulfonate groups from the taurine itcontains no further ionogenic or ionic groups. A film obtained from thelatex, therefore, is insoluble in water without dispersants. Theresulting latex is then reacted with casein and formaldehyde to give theabovementioned reaction product. However, no cosmetic application ofsuch polymers has yet been described.

Film-forming polymers are used in cosmetology to improve the structureof and to shape and set the hair. The hair treatment compositionsgenerally comprise a solution of the film former in an alcohol or in amixture of alcohol and water.

U.S. Pat. No. 4,743,673 describes hydrophilic polyurethane polymers withcarboxyl groups in the polymer backbone. These polyurethanes aresynthesized from a polyol component, which can be an alkylene glycol, apolyoxyalkylene glycol or a linear polyesterdiol, from a carboxylicester component containing hydroxyl or amino groups, and from an organicisocyanate or isocyanate precursor. The polyurethane therefore containsester groups attached to the polymer backbone, which are subsequentlyhydrolyzed by heating under reflux for 30-60 minutes with a strong base,such as sodium hydroxide or potassium hydroxide. The product no longergives a clear solution either in water or in ethanol. Especially whenusing a polyesterdiol as polyol component, treatment with the strongbase under reflux conditions gives rise to hydrolysis not only of theester groups of the carboxylic ester component but also of those presentin the polyurethane chain. The latter is thus cleaved, with a drasticreduction in the molecular weight of the polyurethanes. Admittedly, useof polyurethanes in hairsprays is mentioned; however, the films obtainedwith these polyurethanes cannot in practice be used for hair cosmetologysince they are either insoluble in water or have an inadequate molecularweight and therefore an insufficient setting effect.

DE-A-42 25 045 describes the use of water-soluble or water-dispersibleanionic polyurethanes as hair lacquers. These polyurethanes are composedof

a) at least one compound containing two or more active hydrogen atomsper molecule,

b) at least one diol containing acid groups or salt groups, and

c) at least one diisocyanate.

They have a glass transition temperature of at least 15° C. and an acidnumber of 12-150. Preferred components a) employed are polyethyleneglycol, neopentylglycol and polyesterols. Preferred components b) aredimethylolpropanoic acid, a condensation product of pyromelliticdianhydride and neopentylglycol, and a condensation product of5-sodium-sulfonatoisophthalic acid with neopentylglycol.

DE-A-42 41 118 describes the use of cationic polyurethanes and polyureasas auxiliaries in cosmetic and pharmaceutical formulations. They areemployed in particular as a film former in hair lacquers, and arecomposed of

a) at least one diisocyanate which can have already been reactedbeforehand with one or more compounds containing two or more activehydrogen atoms per molecule, and

b) at least one diol, primary or secondary amino alcohol, primary orsecondary diamine or primary or secondary triamine having one or moretertiary, quaternary or protonated tertiary amine nitrogen atoms.

The polymers have a glass transition temperature of at least 25° C. andan amine number of 50-200, based on the nonquaternized or protonatedcompounds.

EP-A-619 111 describes the use of polyurethanes containing carboxylategroups in hairsetting compositions. To provide the carboxylate groupsthe polyurethanes comprise a compound of the formula

in which A is hydrogen or C₁-C₂₀-alkyl. At least some of the carboxylicacid groups are then neutralized with an organic or inorganic base inorder to provide the number of carboxylate groups required to render thepolyurethane soluble in water or in a mixture of water and a polarorganic solvent.

Hairsetting compositions are generally applied to the hair by sprayingin the form of aqueous-alcoholic solutions. After solvent evaporation,the hair is held in the desired shape at the points of mutual contact ofthe residual polymer. The polymers should be sufficiently hydrophilic toenable washoff from the hair but sufficiently hydrophobic for thepolymer-treated hair to retain its shape, even in the case of highatmospheric humidity, and for the individual hairs not to stick to oneanother. For a maximum hairsetting effect it is additionally desirableto employ polymers with a relatively high molecular weight (K value>25)and a relatively high glass transition temperature (at least 15° C.).However, the higher molecular weight of polymers meeting theserequirements reduces the ease of washoff.

When formulating hair lacquers, another factor to consider is that areduction in the content of alcohol and of propellent is necessary owingto environmental regulations regarding the control of the emission ofvolatile organic compounds (VOCs) into the atmosphere.

The polymers described in the abovementioned publications go only partway to meeting these contradictory requirements. For instance, althoughthe high molecular weight of the polymers described in DE-A-42 25 045and 42 41 118 and in EP-A-619 111 give them the desired setting effect,they are not sufficiently easy to wash off. The polymers described inU.S. Pat. No. 4,743,673, in turn, because of the low molecular weightwhich they have as a result of hydrolysis of the ester groups, do notpossess the required setting effect.

EP-A-636 361 describes cosmetic compositions which include as a filmformer a polycondensation product comprising at least one polysiloxaneunit and at least one polyurethane unit and/or polyurea unit havinganionic or cationic groups. The ease of washoff of these film formers isalso not satisfactory.

It is therefore the object of the present invention to provide hairtreatment compositions which can be used as hair lacquers but which alsohave improve ease of washoff (redispersibility).

We have found that this object can be achieved, surprisingly, by meansof water-soluble or water-dispersible polyurethanes which are thereaction product of a urethane prepolymer having terminal isocyanategroups with a primary or secondary amine which has at least oneionogenic or ionic group.

The present invention therefore provides water-soluble orwater-dispersible polyurethanes of

A) a water-soluble or -dispersible polyurethane prepolymer havingterminal isocyanate groups, and

B) at least one primary or secondary amine which has at least oneionogenic or ionic group, and the salts thereof.

The primary or secondary amine reacts with the terminal isocyanategroups of the urethane prepolymer so that the amine is attached to thepolyurethane via a urea group. Therefore, the novel polyurethanescontain terminal groups which are derived from the amine and each haveat least one ionogenic or ionic group. They preferably have a K value of15-100, in particular 20-50, and a glass transition temperature T_(g) of15-150, in particular 25-100.

If the polyurethanes comprise carboxyl or sulfo groups, the acid numberis preferably 12-150, in particular 30-90.

If the polyurethanes comprise amine groups and/or protonated orquaternized amine groups, the amine number is preferably 30-180, inparticular 50-120.

Polyurethane prepolymers which can be used in accordance with theinvention are known. These are polyurethanes which have ionogenic orionic groups attached to the polymer chain, thereby rendering thepolyurethanes dispersible or soluble in water. These groups arepreferably carboxyl groups and/or sulfo groups and/ornitrogen-containing groups (amines) or carboxylate groups and/orsulfonate groups and/or quaternized or protonated groups. Suchpolyurethane prepolymers are formed from:

a) at least one compound containing two or more active hydrogen atomsper molecule,

b) at least one compound containing two or more active hydrogen atomsand at least one ionogenic or ionic group per molecule, and

c) at least one diisocyanate.

Component (a) especially comprises diols, diamines, amino alcohols,polyetherdiols and polyesterdiols having a number-average molecularweight of in each case up to 3,000, or mixtures thereof, it beingpossible for up to 3 mol-% of said compounds to be replaced by triols ortriamines. A particularly preferred component (a) employed is a diolmixture comprising at least 30% by weight, in particular 40-80% byweight, based on the overall weight of components (a) and (b), of apolyesterdiol.

Examples of diols which can be used are ethylene glycol, propyleneglycol, butylene glycol, neopentylglycol, polyetherols, such aspolyethylene glycols having molecular weights of up to 3,000, blockcopolymers of ethylene oxide and propylene oxide having number-averagemolecular weights of up to 3,000, or block copolymers of ethylene oxide,propylene oxide and butylene oxide in which the copolymerized alkyleneoxide units are present, in random distribution or in the form ofblocks. Preference is given to ethylene glycol, neopentylglycol, anddi-, tri-, tetra-, penta- or hexaethylene glycol.

Examples of suitable amino alcohols are 2-aminoethanol,2-(N-methylamino)ethanol, 3-aminopropanol and 4-aminobutanol.

Examples of suitable diamines are ethylenediamine, propylenediamine,1,4-diaminobutane and 1,6-diaminohexane, and also α,ω-diamines which canbe prepared by aminating polyalkylene oxides with ammonia.

Suitable polyesterdiols are all those customarily employed for preparingpolyurethanes, especially those based on aromatic dicarboxylic acids,such as terephthalic acid, isophthalic acid, phthalic acid, Na- orK-sulfoisophthalic acid, etc., aliphatic dicarboxylic acids, such asadipic acid or succinic acid, etc., and cycloaliphatic dicarboxylicacids, such as 1,2-, 1,3- or 1,4-cyclohexanedicarboxylic acid. Suitablediols are, especially, aliphatic diols, such as ethylene glycol,propylene glycol, 1,6-hexanediol, neopentyl glycol, diethylene glycol,polyethylene glycols, polypropylene glycols, 1,4-dimethylolcyclohexane,and also poly(meth)acrylatediols of the formula

in which R¹⁰ is H or CH₃ and R¹¹ is C₁-C₁₈-alkyl (especially C₁-C₁₂- orC₁-C₈-alkyl) which have a molar mass of up to about 3000. Diols of thiskind can be prepared in a conventional manner and are obtainablecommercially (Tegomer® grades MD, BD and OD from Goldschmidt).

Preference is given to polyesterdiols based on aromatic and aliphaticdicarboxylic acids and on aliphatic diols, especially those for whichthe aromatic dicarboxylic acid makes up from 10 to 95 mol-%, inparticular from 50 to 90 mol-% and, preferably from 70 to 85 mol-%, ofthe overall amount of dicarboxylic acid (the remainder being aliphaticdicarboxylic acids).

Particularly preferred polyesterdiols are the reaction products ofphthalic acid/diethylene glycol, isophthalic acid/1,4-butane-diol,isophthalic acid/adipic acid/1,6-hexanediol, 5-NaSO₃-isophthalicacid/phthalic acid/adipic acid/1,6-hexanediol, adipic acid/ethyleneglycol, isophthalic acid/adipic acid/neopentyl glycol, isophthalicacid/adipic acid/neopentyl glycol/diethylene glycol/dimethylolhexane and5-NaSO₃-isophthalic acid/isophthalic acid/adipic acid/neopentylglycol/diethylene glycol/dimethylolcyclohexane.

The polyesterdiols preferably have a molar mass in the range from about400 to 5000, in particular from 500 to 3000.

Polyurethanes based on these polyesterdiols and on aliphaticdiisocyanates are of particular advantage because they arebiodegradable.

As component (a) it is also possible to use silicone compounds of theformula

where R⁸ and R⁹ can be identical or different and are C₁-C₄-alkyl,benzyl or phenyl, preferably methyl,

the radicals X can be identical or different and are OH or NH₂,

m is 2-8, and

n is 5-50, especially 3-30.

These silicone compounds can be employed in a quantity of up to 50% byweight, in particular up to 30% by weight, based on the overall weightof components (a) and (b).

The polysiloxane-containing polyurethanes act as solubilizers forhydrophobic products, especially silicones, and therefore permit them tobe included in the hair treatment compositions. The silicones make thehair shiny, soft and smooth and are preferably present in amounts of upto 0.2% by weight, based on the overall weight of the composition. It ispreferred to use nonvolatile silicones, especially those based onpoly(dimethylsiloxane).

Particularly suitable silicones are dimethicones, examples being theAbil® grades from Goldschmidt.

If compounds with carboxylate groups or sulfonate groups are employed ascomponent (b), anionic polyurethanes are obtained. A particularlypreferred component (b) is dimethylolpropanoic acid. Other compoundswhich can be used are those of the formulae

where each R is C₂-C₁₈-alkylene and Me is Na or K.

Other compounds which can be used as component (b) are those of theformula

H₂N(CH₂)_(n)—NH—(CH₂)_(m)—COO—M⁺

H₂N(CH₂)_(n)—NH—(CH₂)_(m)—SO₃—M⁺

where m and n independently of one another are an integer from 1 to 8,especially 1 to 6, and M is Li, Na or K.

If compounds with nitrogen-containing groups are used as component (b),cationic polyurethanes are obtained. Examples of components (b) whichcan be used are compounds of the general formulae

where

R¹ and R² can be identical or different and are C₂-C₈-alkylene,

R³, R⁶ and R⁷ can be identical or different and are C₁-C₆-alkyl, phenylor phenyl-C₁-C₄-alkyl,

R⁴ and R⁵ can be identical or different and are H or C₁-C₆-alkyl, o is1, 2 or 3, and

X^(⊖) is chloride, bromide, iodide, C₁-C₆-alkyl sulfate or SO₄ ²⁻/₂.

Component (c) comprises customary diisocyanates, especiallyhexamethylene diisocyanate, isophorone diisocyanate, methyldiphenyldiisocyanate (MDI) and/or tolylene diisocyanate.

Further novel polyurethane prepolymers are described in U.S. Pat. Nos.3,475,206 and 3,412,054 and in DE-A-15 70 615, for example. Use ispreferably made, however, of the polyurethanes described in DE-A-42 25045, DE-A-42 41 118 and EP-A-619 111. The compounds involved are asfollows:

1. Water-soluble or -dispersible anionic polyurethanes of

a) at least one compound containing two or more active hydrogen atomsper molecule,

b) at least one diol containing acid groups or salt groups, and

c) at least one diisocyanate,

which have a glass transition temperature of at least 15° C. and an acidnumber of 12-150, and the salts thereof.

Components (a), (b) and (c) are as described above.

These polymers and their preparation are described in more detail inDE-A-42 25 045, to which in its entirety reference is hereby made.

2. Water-soluble or -dispersible cationic polyurethanes and polyureas,in which context the abovementioned components (a) to (c) are used. Ascomponent (c) it is also possible to use a diisocyanate which can havealready been reacted beforehand with one or more compounds containing 2or more active hydrogen atoms per molecule, i.e. with components (a).

Such polyurethanes and their preparation are described in more detail inDE-A-42 41 118, to which in its entirety reference is hereby made.

3. Linear polyurethanes having carboxylate groups from

a) 10-90% by weight, based on the weight of the polyurethane, of one ormore organic compounds having not more than two active hydrogen atoms,

b) a 2,2-hydroxymethyl-substituted carboxylic acid of the formula

 where A is hydrogen or C₁-C₂₀-alkyl, which is used in a quantitysufficient for 0.35-2.25 milliequivalents of carboxyl groups to bepresent per g of polyurethane, and

c) one or more organic diisocyanates.

Components a) and c) are as indicated above.

Finally, the carboxyl groups present in the polyurethane are at leastpartially neutralized with an appropriate base. These polymers and theirpreparation are described in more detail in EP-A-619 111, to which inits entirety reference is hereby made.

The polyurethane prepolymers are obtainable by reacting the compounds ofgroups a) and b) with the compounds of group c) at 70-130° C. in aninert solvent or without a solvent (in the melt) under an inert gasatmosphere, and using the components in quantities such that the ratioof NCO equivalent to OH equivalent is greater than 1 and can be up to1.2, but is preferably from 1.02 to 1.12. The acid number of thepolyurethanes is determined by the composition and the concentration ofthe compounds of component (b) in the mixture of components (a)+(b). Thepolyurethanes have H. Fikentscher K values (determined in 0.1% strengthby weight solutions in N-methylpyrrolidone at 25° C. and a pH of 7) of15-100, preferably 25-50.

In accordance with a preferred embodiment, component (B) is an amine ofthe formula:

R¹⁰HN—Y—SO₃H

where Y is o-, m- or p-phenylene or straight-chain or branchedC₂-C₆-alkylene which is unsubstituted or substituted by 1, 2 or 3hydroxyl groups, and

R¹⁰ is hydrogen, C₁-C₁₂-alkyl (preferably C₁-C₁₀-alkyl and especiallyC₁-C₆-alkyl) or C₅-C₆-cycloalkyl, it being possible for the alkyl orcycloalkyl to be substituted, if desired, by 1, 2 or 3 hydroxyl,carboxyl or sulfo groups.

The amine of the above formula is particularly preferably taurine,N-(1,1-dimethyl-2-hydroxyethyl)-3-amino-2-hydroxypropanesulfonic acid or4-aminobenzenesulfonic acid.

In accordance with a further preferred embodiment the amine is acustomary α-, β- or γ-amino acid, for example glycine, alanine, valine,leucine, isoleucine, phenylalanine, thyrosine, proline, hydroxyproline,serine, threonine, methionine, cysteine, tryptophan or β-alanine.Preferred amino acids are aspartic acid and glutamic acid.

The novel polyurethanes are prepared by reacting the polyurethaneprepolymer with the primary or secondary amine having an ionogenic orionic group, in an appropriate inert solvent or without a solvent (inthe melt). The quantity of amine used is such that the free isocyanategroups of the polyurethane prepolymer are at least partially reacted,but preferably completely reacted. Reaction is carried out in a mannerknown from the prior art for the termination of polyurethanepolymerization with amines. Any isocyanate groups still present aresubsequently deactivated by adding amines, for example2-amino-2-methyl-1-propanol.

After replacing the solvent by water a solution or dispersion of thepolymer is obtained from which the polymer can, if desired, be obtainedin a customary manner, for example by spray drying.

The amine is preferably employed in the form of an aqueous oraqueous-alcoholic solution with a pH of >7.5, in order to increase thereactivity of the amine. The pH can be established in a customarymanner, for example using an alkali metal hydroxide such as NaOH or KOH,or, preferably, using a tertiary amine such as triethylamine, aC₁-C₆-alkyldiethanolamine, for example methyl- or ethyldiethanolamine,or a di-C₁-C₆-alkylethanolamine.

After complete or partial neutralization, the polyurethanes containingacid groups are soluble in water or dispersible in water without the aidof emulsifiers. In general the resulting polyurethane salts are moresoluble or dispersible in water than the non-neutralized polyurethanes.Suitable bases for neutralizing the polyurethanes are alkali metalbases, such as sodium hydroxide, potassium hydroxide, sodium carbonate,sodium hydrogen carbonate, potassium carbonate and potassium hydrogencarbonate, and alkaline earth metal bases, such as calcium hydroxide,calcium oxide, magnesium hydroxide and magnesium carbonate, and alsoammonia and amines. Compounds which have proven particularly suitable,in the context of use in hair treatment compositions, for neutralizingthe polyurethanes containing acid groups are 2-amino-2-methylpropanol,diethylaminopropylamine and triisopropanolamine. The polyurethanescontainig acid groups can also be neutralized using a mixture of two ormore bases, for example mixtures of sodium hydroxide solution andtriisopropanolamine. Depending on the intended application,neutralization may be partial, eg. 20-40%, or complete, ie. 100%.

Where the novel compounds are dispersible in water they can be employedin the form of aqueous microdispersions with particle diameters ofusually 5-100 nm, in particular 10-80 nm, and solids contents of usually1-40% by weight, in particular 3-30% by weight. These microdispersionsdo not in general require any emulsifiers or surfactants in order tostabilize them.

The polyurethanes and polyureas containing free, protonated orquaternized amine groups are in general, owing to their cationic groups,readily soluble in alcohols and water, or can at least be dispersed inalcohol and water without the aid of emulsifiers. Charged cationicgroups can be produced in the polyureas from the existing tertiary aminenitrogen atoms either by protonation, for example with carboxylic acidssuch as lactic acid, or by quaternization, for example with alkylatingagents such as C₁-C₄-alkyl halides or C₁-C₄-alkyl sulfates. Examples ofsuch alkylating agents are ethyl chloride, ethyl bromide, methylchloride, methyl bromide, dimethyl sulfate and diethyl sulfate.

The novel polyurethanes can be used as auxiliaries in cosmetology andpharmacy, especially as coating compositions for keratin-containingsurfaces (hair, skin and nails) and as coatings and/or binders for soliddrug forms. They can additionally be used as coating compositions forthe textile, paper, printing and adhesives industries. They areparticularly suitable for use in hair cosmetology. Preferredpolyurethanes employed as hair lacquers are those comprising at least30% by weight of polyesterdiol component and having a glass transitiontemperature T_(g) of ≧25° C. In addition, the polymers can also be usedin creams and as coatings and binders for tablets.

The present invention additionally provides a cosmetic or pharmaceuticalcomposition comprising the novel polyurethanes, generally in a quantityof 0.2-20% of the overall weight of the composition.

Preference is given to hair treatment compositions. These are usually inthe form of an aqueous dispersion or an alcoholic or aqueous-alcoholicsolution. Examples of appropriate alcohols are ethanol, propanol,isopropanol, etc.

Furthermore, the novel hair treatment compositions generally comprisecustomary cosmetic auxiliaries, examples being softeners, such asglycerol and glycol; emollients; fragrances; UV absorbers; colorants;thickeners; antistats; combability improvers; preservatives; and foamstabilizers.

When formulated as hairsprays, the novel compositions comprise asufficient quantity of a propellent, for example a low-boilinghydrocarbon or ether, such as propane, butane, isobutane or dimethylether. As propellents it is also possible to use compressed gases, suchas nitrogen, air or carbon dioxide. The amount of propellent is kept aslow as possible so as not unnecessarily to raise the VOC content. Ingeneral it is not more than 40% of the overall weight of thecomposition.

The polyurethanes of the invention can also be employed in thecompositions in combination with other hair polymers. Such polymers are,in particular:

nonionic, water-soluble or water-dispersible polymers or oligomers, suchas polyvinylcaprolactam, eg. Luviskol Plus (BASF), orpolyvinylpyrrolidone and its copolymers, especially with vinyl esterssuch as vinyl acetate, eg. Luviskol VA 37 (BASF); polyamides, forexample those based on itaconic acid and aliphatic diamines

amphoteric or zwitterionic polymers, such as the octylacrylamide/methylmethacrylate/tert-butylaminoethyl methacrylate/2-hydroxypropylmethacrylate copolymers obtainable under the designations Amphomer®(Delft National), and zwitterionic polymers as disclosed, for example,in German Patent Applications DE 39 29 973, DE 21 50 557, DE 28 17 369and DE 37 08 451. Acrylamidopropyltrimethyl-ammonium chloride/acrylicacid and/or methacrylic acid copolymers, and the alkali metal salts andammonium salts thereof, are preferred zwitterionic polymers. Suitablezwitterionic polymers are also methacroylethyl betaine/methacrylatecopolymers, which are obtainable commercially under the designationAmersette® (AMERCHOL).

water-soluble or water-dispersible polymers with the same ionogenicityas the polymers of the invention, ie.

anionic polyurethanes of the invention and anionic polymers, such asvinyl acetate/crotonic acid copolymers, as are in commerce, for example,under the designations Resyn® (NATIONAL STARCH), Luviset® (BASF) andGafset® (GAF), vinylpyrrolidone/vinyl acrylate copolymers, obtainablefor example under the trademark Luviflex® (BASF). A preferred polymer isthe vinylpyrrolidone/acrylate terpolymer obtainable under thedesignation Luviflex® VBM-35 (BASF), acrylic acid/ethylacrylate/N-tert-butylacrylamide terpolymers, which are marketed, forexample, under the designation Ultrahold® strong (BASF), and Luvimer®(BASF, terpolymer of t-butyl acrylate, ethyl acrylate and methacrylicacid), or

cationic polyurethanes of the invention and cationic (quaternized)polymers, eg. Luviquat® (copolymer of vinylpyrrolidone andvinylimidazolium methochloride), Luviquat® Hold (copolymer ofquaternized N-vinylimidazole, N-vinylpyrrolidone andN-vinylcaprolactam), Merquat® (polymer based on dimethyldiallylammoniumchloride) Gafquat® (quaternary polymers formed by reactingpolyvinylpyrrolidone with quaternary ammonium compounds), Polymer JR(hydroxyethylcellulose with cationic groups), polyquaternium types (CTFAnames), etc.

neutral, siloxane-containing, water-soluble or -dispersible polymers,eg. polyethersiloxanes, such as Tegopren® (Goldschmidt).

The other hair polymers are preferably present in amounts of up to 10%by weight, based on the overall weight of the composition. Aparticularly preferred hair treatment composition comprises:

a) at least one siloxane-free, water-soluble or -dispersible hairpolymer, especially hairsetting polymer, which can be either apolyurethane of the invention or another hair polymer,

b) at least one polysiloxane-containing polyurethane as defined aboveand

c) a water-insoluble non-volatile silicone, especially apolydimethylsiloxane, eg. the Abil grades from Goldschmidt.

The composition preferably contains 0.1-10% by weight of component a),0.1-15% by weight of component b) and from 0.0001 to 0.2% by weight ofcomponent c).

The novel polyurethanes and compositions have the advantage that firstlythey give the hair the desired set and secondly the polymers are easierto wash off (more redispersible) than their prior art counterparts.Furthermore, it is possible to formulate hair treatment compositionswith a VOC content of less than 60% by weight and also to prepare purelyaqueous formulations, even if they are formulated as hairsprays.

The examples which follow illustrate the invention.

EXAMPLE 1

Polyurethane preparation:

0.5 mol of polyesterdiol (M_(w)=1,000 g/mol, prepared from isophthalicacid, adipic acid and hexanediol), 0.6 mol of diethylene glycol and 1.25mol of dimethylolpropanoic acid in methyl ethyl ketone (about 50%strength) were heated to 80° C. with stirring to form a solution in a4-necked flask fitted with stirrer, dropping funnel, thermometer, refluxcondenser and a device for working under nitrogen. Immediately aftercomplete dissolution, the reaction mixture was cooled to about 50° C.Then 2.5 mol of isophorone diisocyanate were added dropwise, whilestirring, and the reaction temperature rose. At an internal temperatureof 90° C., the reaction mixture was then stirred until its content ofisocyanate groups remained virtually constant. It was then cooled toambient temperature, at which 0.3 mol of (a) aspartic acid or (b)glutamic acid or (c) taurine was added, in each case in the form of a50% strength aqueous solution of amino acid and diethylethanol-amine,the latter being used in a quantity equimolar with the amino acid. Thereaction mixture was then stirred at ambient temperature until itscontent of isocyanate groups was 0. Water was then added and thereaction product was neutralized with 2-amino-2-methylpropanol. Themethyl ethyl ketone was then distilled off under reduced pressure at 40°C. to give an aqueous polyurethane dispersion which was used for thetests described in Examples 3 and 4 below.

EXAMPLE 2

Polyurethane preparation (without adding an amino acid)

0.5 mol of polyesterdiol (M_(w)=1,000 g/mol, prepared from isophthalicacid, adipic acid and hexanediol), 0.5 mol of diethylene glycol and 1.25mol of dimethylolpropanoic acid in methyl ethyl ketone (about 50%strength) were heated to 80° C. with stirring to form a solution in a4-necked flask fitted with stirrer, dropping funnel, thermometer, refluxcondenser and a device for working under nitrogen. Immediately aftercomplete dissolution, the reaction mixture was cooled to about 50° C.Then 2.5 mol of isophorone diisocyanate were added dropwise, whilestirring, and the reaction temperature rose. At a reflux temperature,the reaction mixture was then stirred until its content of isocyanategroups remained virtually constant. The residual isocyanate groups weredeactivated by adding an amine, for example 2-amino-2-methyl-1-propanol.Free COOH groups were neutralized with 2-amino-2-methylpropanol. Waterwas then added and the largest part of the methyl ethyl ketone wasremoved under reduced pressure at about 40° C. to give a polyurethanedispersion which was used for comparison for the tests described inExample 4 below.

EXAMPLE 3

Determination of the ease of washoff of the polymers:

The ease of washoff with water of the polymers obtained as described inExample 1 was compared with that of a polymer in which the terminalisocyanate groups have been reacted not with an amino acid but with2-amino-2-methylpropanol. For this purpose, a film obtained from a 5%strength aqueous dispersion and a film obtained from an aqueousethanolic dispersion (1:1 v/v) of the polymer were produced on a glassplate by pouring the individual polymer dispersion onto the glass plateand then drying it at room temperature for 20 h. The ease of washoff(redispersibility) of the film prepared from water or water/ethanol (1:1v/v) was determined by rubbing with the finger. The results obtained areindicated in the table below.

TABLE Ease of washoff of the polymers Ease of washoff Film from Filmfrom K value of the Amino aqueous H₂O/EtOH Test polyurethane aciddispersion dispersion 1 27 — poor poor 2 27 Asp good good 3 27 Glu goodgood 4 27 Tau good good Asp = aspartic acid Glu = glutamic acid Tau =taurine

It is evident that, surprisingly, the films obtained with the novelcompositions are easier to wash off than the film obtained with theprior art composition.

EXAMPLE 4

Hairspray formulation with a VOC content of 55% by weight: Polyurethaneof Example 1  5.00% by wt. (solids content) Water 40.00% by wt. Ethanol25% by wt. Dimethyl ether 30% by wt. Fragrance q.s.

The ease of washoff of the film obtained with this formulation wascompared with that of a film obtained with the same formulation butcontaining the polyurethane as described in Example 2. The ease ofwashoff was determined as follows:

The hairspray was applied in a 10-second spray procedure (quantityapplied about 2.5 g) to the hair of synthetic headforms. After dryingfor two hours in a climate-controlled room (atmospheric humidity 45%;temperature 20° C.), the setting effect was assessed. This procedure wasrepeated a total of 3 times. The sprayed headform was dried overnight inthe climate-controlled room and then shampooed with Texapon NSO forminutes or less and washed. After drying, the ease of washoff wasassessed by trained technical staff. It was found that the film obtainedwith the novel formulation was easy to wash off, whereas washoff of thefilm obtained with the polyurethane as described in Example 2 wasdifficult.

We claim:
 1. A water-soluble or water-dispersible polyurethane or a saltthereof comprising A) a water-soluble or -dispersible polyurethaneprepolymer having terminal isocyanate groups formed from a) at least onecompound containing two or more active hydrogen atoms per moleculeselected from diols, diamines, aminoalcohols, polyetherdiols,polyesterdiols each with a number average molecular weight of up to3000, or mixtures thereof, wherein if the at least one compound ofcomponent a) comprises a polyesterdiol then the polyesterdiol is thereaction product of an aromatic dicarboxylic acid and an aliphaticdicarboxylic acid and an aliphatic diol, b) at least one compounddifferent from the at least one compound of component a), containing twoor more active hydrogen atoms and at least one ionogenic or ionic groupper molecule which is a carboxylate group or nitrogen-containing group,wherein if the at least one compound of component b) contains anitrogen-containing group, then the at least one compound of componentb) is selected from the group consisting of

where R¹ and R² are identical or different and are C₂-C₈-alkylene, R³,R⁶ and R⁷ are identical or different and are C₁-C₆-alkyl, phenyl orphenyl-C₁-C₄-alkyl, R⁴ and R⁵ are identical or different and are H orC₁-C₆-alkyl, o is 1, 2 or 3, and X⁻ is chloride, bromide, iodide,C₁-C₆-alkyl sulfate or SO₄ ²⁻/2, and c) at least one diisocyanateselected from isophorone diisocyanate, methylenediphenyl diisoscyanateor toluylene diisocyanate, and B) at least one primary or secondaryamine having at least one ionogenic or ionic group; wherein component a)comprises an amount up to 50% by weight, based on the overall weight ofcomponents a) and b), of a silicone compound of the formula

where R⁸ and R⁹ are identical or different and are C₁-C₄-alkyl, benzylor phenyl, the radicals X are identical or different and are OH or NH₂,m is 2-8, and n is 3-50.
 2. A polyurethane as claimed in claim 1, wherecomponent (a) is a polyesterdiol which is the reaction product of anaromatic dicarboxylic acid and an aliphatic dicarboxylic acid and analiphatic diol.
 3. A polyurethane as claimed in claim 2, where theproportion of the aromatic dicarboxylic acid makes up from 10 to 95mol-% of the overall dicarboxylic acid.
 4. A polyurethane as claimed inclaim 2, where the proportion of the aromatic dicarboxylic acid makes upfrom 40 to 90 mol-% of the overall dicarboxylic acid.
 5. A polyurethaneas claimed in claim 2, where the proportion of the aromatic dicarboxylicacid makes up from 50 to 85 mol-% of the overall dicarboxylic acid.
 6. Apolyurethane as claimed in claim 1, wherein component a) comprises 40 to80 % by weight, based on the overall weight of components a) and b), ofa polyesterdiol.
 7. A polyurethane as claimed in claim 1, wherein up to3 mol-% of the at least one compound of component a) is replaced bytriols or triamines.
 8. A polyurethane as claimed in claim 1, whereinthe ratio of NCO equivalent of the compounds of group c) to equivalentof active hydrogen atom of the compounds of group a) and b) is fromgreater than 1:1 to 1.2:1.
 9. A polyurethane as claimed in claim 1,wherein component b) is dimethylolpropanoic acid.
 10. A polyurethane asclaimed in claim 1, wherein component a) comprises at least 30% byweight based on the overall weight of components a) and b), of apolyesterdiol.
 11. A polyurethane as claimed in claim 1, whereincomponent (B) is an aminosulfonic acid of the formula R¹⁰HN—Y—SO₃H whereY is o-, m- or p-phenylene or straight-chain or branched C₂-C₆-alkylenewhich is unsubstituted or substituted by 1, 2 or 3 hydroxyl groups, andR¹⁰ is hydrogen, C₁-C₁₂-alkyl or C₅-C₆-cycloalkyl, wherein the alkyl orcycloalkyl are optionally substituted by 1, 2 or 3 hydroxyl, carboxyl orsulfo groups.
 12. A polyurethane as claimed in claim 11, wherein theamine is taurine,N-(1,1-dimethyl-2-hydroxyethyl)-3-amino-2-hydroxy-propanesulfonic acidor 4-aminobenzenesulfonic acid.
 13. A process for preparing apolyurethane as claimed in claim 1, which comprises reacting thepolyurethane prepolymer with a primary or secondary amine.
 14. Awater-soluble or water-dispersible polyurethane or a salt thereofcomprising A) a water-soluble or -dispersible polyurethane prepolymerhaving terminal isocyanate groups formed from a) at least one compoundcontaining two or more active hydrogen atoms per molecule selected fromdiols, diamines, aminoalcohols, polyetherdiols, polyesterdiols each witha number average molecular weight of up to 3000, or mixtures thereof,wherein if the at least one compound of component a) comprises apolyesterdiol then the polyesterdiol is the reaction product of anaromatic dicarboxylic acid and an aliphatic dicarboxylic acid and analiphatic diol, b) at least one compound different from the at least onecompound of component a), containing two or more active hydrogen atomsand at least one ionogenic or ionic group per molecule which is acarboxylate group or nitrogen-containing group, wherein if the at leastone compound of component b) contains a nitrogen-containing group, thenthe at least one compound of component b) is selected from the groupconsisting of

where R¹ and R² are identical or different and are C₂-C₈-alkylene, R³,R⁶ and R⁷ are identical or different and are C₁-C₆-alkyl, phenyl orphenyl-C₁-C₄-alkyl, R⁴ and R⁵ are identical or different and are H orC₁-C₆-alkyl, o is 1, 2 or 3, and X⁻ is chloride, bromide, iodide,C₁-C₆-alkyl sulfate or SO₄ ²⁻/2, and c) at least one diisocyanateselected from isophorone diisocyanate, methylenediphenyl diisoscyanateor toluylene diisocyanate, and B) at least one primary or secondaryamine having at least one ionogenic or ionic group, wherein component(B) is an α-, β- or γ-aminocarboxylic acid.
 15. A polyurethane asclaimed in claim 14, wherein the amino acid is aspartic acid or glutamicacid.
 16. A cosmetic or pharmaceutical composition comprising at leastone water-soluble or water-dispersible polyurethane or a salt thereofcomprising A) a water-soluble or -dispersible polyurethane prepolymerhaving terminal isocyanate groups formed from a) at least one compoundcontaining two or more active hydrogen atoms per molecule selected fromdiols, diamines, aminoalcohols, polyetherdiols, polyesterdiols each witha number average molecular weight of up to 3000, or mixtures thereof, b)at least one compound different from the at least one compound ofcomponent a), containing two or more active hydrogen atoms and at leastone ionogenic or ionic group per molecule which is a carboxylate groupor nitrogen-containing group, wherein if the at least one compound ofcomponent b) contains a nitrogen-containing group, then the at least onecompound of component b) is selected from the group consisting of

where R¹ and R² are identical or different and are C₂-C₈-alkylene, R³,R⁶ and R⁷ are identical or different and are C₁-C₆-alkyl, phenyl orphenyl-C₁-C₄-alkyl, R⁴ and R⁵ are identical or different and are H orC₁-C₆-alkyl, o is 1, 2 or 3, and X⁻ is chloride, bromide, iodide,C₁-C₆-alkyl sulfate or SO₄ ²⁻/2, and c) at least one diisocyanateselected from isophorone diisocyanate, methylenediphenyl diisoscyanateor toluylene diisocyanate, and B) at least one primary or secondaryamine having at least one ionogenic or ionic group.
 17. A composition asclaimed in claim 16, wherein component a) comprises up to 50% by weight,based on the overall weight of components a) and b), of a siliconecompound of the formula

where R⁸ and R⁹ are identical or different and are C₁-C₄-alkyl, benzylor phenyl, the radicals X are identical or different and are OH or NH₂,m is 2-8, and n is 3-50, said composition further comprising at leastone water-insoluble silicone.
 18. A composition as claimed in claim 17,wherein the water-insoluble silicone is polydimethylsiloxane.
 19. Acomposition as claimed in claim 17, further comprising at least onesiloxane-free, water soluble or -dispersible hair polymer.
 20. Acomposition as claimed in claim 19, wherein the water-insoluble siliconeis polydimethylsiloxane.
 21. A hair treatment composition comprising atleast one water-soluble or water-dispersible polyurethane or a saltthereof comprising A) a water-soluble or -dispersible polyurethaneprepolymer having terminal isocyanate groups formed from a) at least onecompound containing two or more active hydrogen atoms per moleculeselected from diols, diamines, aminoalcohols, polyetherdiols,polyesterdiols each with a number average molecular weight of up to3000, or mixtures thereof, b) at least one compound different from theat least one compound of component a), containing two or more activehydrogen atoms and at least one ionogenic or ionic group per moleculewhich is a carboxylate group or nitrogen-containing group, wherein ifthe at least one compound of component b) contains a nitrogen-containinggroup, then the at least one compound of component b) is selected fromthe group consisting of

where R¹ and R² are identical or different and are C₂-C₈-alkylene, R³,R⁶ and R⁷ are identical or different and are C₁-C₆-alkyl, phenyl orphenyl-C₁-C₄-alkyl, R⁴ and R⁵ are identical or different and are H orC₁-C₆-alkyl, o is 1, 2 or 3, and X⁻ is chloride, bromide, iodide,C₁-C₆-alkyl sulfate or SO₄ ²⁻/2, and c) at least one diisocyanateselected from isophorone diisocyanate, methylenediphenyl diisoscyanateor toluylene diisocyanate, and B) at least one primary or secondaryamine having at least one ionogenic or ionic group.
 22. A composition asclaimed in claim 21, which additionally comprises at least one otherwater-soluble or -dispersible hair polymer.
 23. A hairspray comprisingat least one water-soluble or water-dispersible polyurethane or a saltthereof comprising A) a water-soluble or -dispersible polyurethaneprepolymer having terminal isocyanate groups formed from a) at least onecompound containing two or more active hydrogen atoms per moleculeselected from diols, diamines, aminoalcohols, polyetherdiols,polyesterdiols each with a number average molecular weight of up to3000, or mixtures thereof, wherein if the at least one compound ofcomponent a) comprises a polyesterdiol then the polyesterdiol is thereaction product of an aromatic dicarboxylic acid and an aliphaticdicarboxylic acid and an aliphatic diol, b) at least one compounddifferent from the at least one compound of component a), containing twoor more active hydrogen atoms and at least one ionogenic or ionic groupper molecule which is a carboxylate group or nitrogen-containing group,wherein if the at least one compound of component b) contains anitrogen-containing group, then the at least one compound of componentb) is selected from the group consisting of

where R¹ and R² are identical or different and are C₂-C₈-alkylene, R³,R⁶ and R⁷ are identical or different and are C₁-C₆-alkyl, phenyl orphenyl-C₁-C₄-alkyl, R⁴ and R⁵ are identical or different and are H orC₁-C₆-alkyl, o is 1, 2 or 3, and X⁻ is chloride, bromide, iodide,C₁-C₆-alkyl sulfate or SO₄ ²⁻/2, and c) at least one diisocyanateselected from isophorone diisocyanate, methylenediphenyl diisoscyanateor toluylene diisocyanate, and B) at least one primary or secondaryamine having at least one ionogenic or ionic group.